武汉理工大学毕业设计（论文）

1070型电动货车后悬架设计

学院（系）： 国际教育学院

专业班级： 车辆GJ1403班

学生姓名： 李根

指导教师： 韩爱国

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Abstract

With the deterioration of environment and energy shortage, we pay more and more attention to environmental protection. Electric vehicles can effectively solve such problems, which have the advantages of low energy consumption, less pollution and less noise. For electric truck, China is at the beginning stage, but it is believed that with the strong support of the state, There will have some great achievements at the electric truck field. At present, some light electric vehicles have been put into use on the market.

This topic is the design of the 1070 type electric truck rear suspension, the main contents including the design and calculation of main parameters about the suspension, and using CATIA to t construct the three-dimensional model of suspension, and perform corresponding finite element analysis on some components in the rear suspension structure. In addition, the vehicle layout of electric truck is analyzed and elaborated accordingly.

Key Words：Electric truck；rear suspension design；CATIA；finite element analysis.

Contents

1 Introduction 1

1.1 The purpose and significance of the thesis research 1

1.2 Research status at home and abroad 2

1.3 The main research content of the thesis 3

2 Overall plan selection 4

2.1 Suspension type 4

2.2 The composition of the suspension and the role of various components 5

2.3 Determination of Suspension Options 5

3 Determination and Calculation of Suspension Technical Parameters 7

3.1 The original parameters of the design 7

3.2 The bias frequency of suspension 7

3.3 The static deflection of suspension 8

3.4 The dynamic deflection of the suspension 9

3.5 Elastic properties of suspension 9

3.6 The stiffness distribution of rear suspension main and auxiliary spring 10

3.7 Lateral inclination stiffness of suspension 12

4 Design of elastic elements 13

4.1 The layout of leaf spring 13

4.2 Determination of main parameters of leaf spring 13

4.2.1 Full load arc height() 13

4.2.2 Determination of length of leaf spring 13

4.2.3 Determination of section size of leaf spring 13

4.2.4 The determination of the length of each leaf spring 15

4.3 Calculation of Arc Height and Curvature Radius of Assemblies at Free Height 19

4.3.1 Height of arc of leaf spring assembly in free state () 19

4.3.2 Determination of curvature radius of leaf spring assembly in free state 20

4.3.3 Determination of the radius of curvature of each leaf spring in free state 20

4.4 Arc spring height calculation of leaf spring assembly 22

4.5 Leaf spring strength check 23

4.5.1 Drive conditions 23

4.5.2 On uneven roads 24

4.7 Check the strength of the leaf spring cotter pin 25

4.8 Material and Technical Requirements for Leaf Springs 25

5 Structural Components of the Suspension 27

5.1 Section shape of the leaf spring 27

5.2 Form of the leaf spring eye 27

5.3 Structure of lifting lug and spring pin 28

6 Finite Element Analysis 30

7 Conclusion 34

References 35

Appendix 36

Acknowledgement 38

1 Introduction

1.1 The purpose and significance of the thesis research

The purpose of this project is to design the rear suspension of the Model 1070 electric truck. The significance is to finds the advantages of using electric energy as an energy source on trucks and the impact on the layout of trucks, and makes some design calculations and analysis about the rear suspension. Electric vehicles has these following advantages: (1) Essentially zero emissions, during the driving process, the car uses electrical energy, no exhaust emissions, and it does not pollute the environment; (2) Electric vehicles have higher energy efficiency than fuel vehicles; (3) Only use a single electric energy source, thus eliminating the need for engines, transmissions, fuel tanks, etc, so the structure is relatively simple; (4) The noise is relatively low; (5) The car can be charged when the electricity at the low peak and the power generation equipment fully utilized. However, electric cars also face some problems at this stage. For example, (1) the cruising range is relatively short; (2) the use of batteries and motor controllers is costly; (3) the battery life is short, and it takes a long time to replace the charging; (4) the charging time is long, especially new The charging infrastructure for energy vehicles is not perfect. Although China’s light electric trucks started late, but they have always been national plans. These include the state’s subsidy policies for new energy vehicles over the past few years and so on, all of which indicate the good prospects for the development of new energy vehicles.

Using electric energy as a power source to drive trucks, then for the entire vehicle layout, there must be a difference in the layout of the vehicle to an ordinary fuel truck. For example, the current automobile frame structure is characterized by strong speciality and high quality, which is not suitable for light-duty electric vehicles. It is necessary to reduce the frame quality when designing, and it is necessary to arrange the power battery and the car wiring conveniently. Or when placing the damper on the rear suspension, it should be as close to the wheel center as possible to ensure uniform force.

For the rear suspension design of trucks, most of the current domestic light trucks use the leaf spring non-independent suspension as the first choice for the rear suspension. In the design and calculation of leaf springs, the design of elastic elements is particularly important.

1.2 Research status at home and abroad

In the past few years, pure electric trucks in the United States have developed in varying degrees in both heavy and light areas. The speed has been significantly improved, and the endurance capacity has been somewhat insufficient. Recently, at MWC2017, American automaker Ford released a new concept unmanned electric truck. In addition to being unmanned, this concept truck can be used as a landing platform for drones to send goods to places where transport is not possible. Purely electric trucks are limited by charging time and cruising range. Currently, they are mainly used for point-to-point short-distance transportation. They cannot yet truly replace the internal-combustion engine trucks and meet the requirements for long-distance transportation. Despite this, several major truck brands in Europe have introduced pure electric products, which shows that the application of pure electric trucks has become a trend within the industry and cannot be overlooked. Previous online shopping giant Amazon plans to launch drone delivery service. London, United Kingdom, plans to test unmanned truck delivery next year to provide 24-hour delivery service, thereby reducing the number of road vehicles during heavy traffic hours and alleviating traffic congestion. And our neighboring country, Japan, is the first country in the world to begin the development of hybrid cars and realize industrialization. Hybrid power technology is a necessary part of the shift from a single engine drive to a purely electric drive, which can significantly reduce fuel consumption and reduce carbon emissions. It is also the key direction of technological development in various countries. As for the field of pure electric vehicles, Japan mainly uses small and light trucks as the mainstream market.

Every span of suspension technology is closely related to the development of related disciplines. Computer technology, automatic control technology, fuzzy control, neural network, advanced manufacturing technology, and motion pseudo-reality provide powerful guarantees for the further development of the suspension. The development of the suspension also puts forward higher requirements for related disciplines and enables human understanding to move toward a new and higher realm.
The existing passive suspension will gradually transition to semi-active and active suspension. The advantages of electric devices will replace hydraulic devices. The development of large-scale and ultra-large-scale integrated circuits will increase the degree of integration of electronic components, thereby promoting reliability and making the suspension more intelligent to meet people's requirements.

1.3 The main research content of the thesis

Suspension design can be divided into structural form and main parameter selection stage and detailed design stage, and sometimes it must be repeated. The main contents of this design include:

1. Determination of dynamic and static deflection of suspension;
2. The stiffness distribution of the main and auxiliary springs of the rear suspension of trucks;
3. Select the correct rear suspension structure and parameters.

2 Overall plan selection

2.1 Suspension type

The type of suspension has two types on two-axle vehicles which are non-independent and independent suspension.

1. Independent suspension: The left and right wheels of the independent suspension can move independently without affecting each other. Its advantages are: the impact load on the suspension is small, the spring with small rigidity can be used, the vibration frequency of the body is low, and the ride comfort is improved. The front suspension uses independent suspension to reduce body tilt and vibration. However, because of its complex structure and high cost, it is mainly used in the front suspension of passenger cars, station wagons and small commercial vehicles.
2. Non-independent suspension: The characteristics of the non-independent suspension is that the left and right wheels are connected by a steel shaft and are connected to the frame (or body) through the suspension. The typical representative is the vertical leaf spring suspension. Compared with independent suspension, its advantages are simple structure, reliable work, convenient maintenance and low cost. When the wheel moves up and down, the change of the wheel alignment is small, and the wear of the tire is small. Therefore, the non-independent suspension is mainly used for commercial trucks, front and rear wheels of city buses, and rear wheels of some passenger cars.